The production of earthworms for bait, animal feed and agricultural purposes is a growing business. Typically, earthworms are raised in worm beds and when the worms are mature they must be separated from the bedding material and from the worm castings. The worm castings have been recognized as a highly effective organic fertilizer and the re-claiming of this resource has become a valuable adjunct to the business of raising earthworms.
The separation of earthworms from other bedding material has classically been carried out by placing the mixture on the upper surface of a screen which is typically tilted or shaken to permit the castings to pass through the screen and to hold the worms on the upper surface of the screen. Such an approach has limited capacity, however, since oversized and agglomerated bedding material quickly clogs the pores of the screen necessitating an interruption of the separating process. While most bedding material would be expected to pass through screen openings of approximately 1/4 to 1/2 inch in size, the mechanical vibration of the screen used in an attempt to increase production tends to agglomerate the bedding material into larger particles. The result is that the bedding material is held on the upper surface of the screen together with the worms and the process must be stopped to perform this secondary separation of bedding material from worms.